1. Technical Field
The present invention relates to a wavelength conversion element, a light source device, and a projector.
2. Related Art
As a light source device used for a projector or the like, a light source device has been proposed which irradiates a phosphor with excitation light emitted from a light source such as a semiconductor laser and uses fluorescence light obtained from the phosphor.
For example, JP-A-2010-86815 discloses a light source device including an excitation light source, a red light-emitting device, a green light-emitting device, and a blue light-emitting device. The light-emitting devices of the respective colors each include a base material having a light-transmissive property, a dichroic layer, and a phosphor layer. Excitation light that is emitted from the excitation light source successively passes through the base material and the dichroic layer, and is then enters the phosphor layer. In fluorescence light that is emitted from the phosphor layer in all directions, fluorescence light that travels toward the base material side is reflected by the dichroic layer and extracted to the side opposite to the base material.
In the light source device disclosed in JP-A-2010-86815, the dichroic layer transmitting the excitation light and reflecting the fluorescence light is provided between the base material and the phosphor layer for extracting the fluorescence light in a desired direction, that is, to the side opposite to the base material. However, in the fluorescence light that is incident on the dichroic layer, a P-polarization component that has an incident angle close to Brewster's angle passes through the dichroic layer. Therefore, the light source device disclosed in JP-A-2010-86815 has a problem in that some components of the fluorescence light cannot be extracted in the desired direction.